The invention relates to a moisture curable, radiation curable sealant composition. More particularly, the invention relates to such sealant compositions for use in insulating glass assemblies.
Insulating glass assemblies such as insulating glass units and insulating sash assemblies often include a pair of glass sheets maintained in a fixed spaced relation to each other by a spacing and sealing structure that extends around the periphery of the inner facing surfaces of the glass sheets to define a sealed and insulating space between the glass sheets. In the case of insulating sash assemblies, the glass panes are adhered to the spacer that is an integral part of the sash frame. The glass sheets are usually attached to the structure by a sealant or adhesive composition.
Sealants and adhesive compositions have been used to seal the edges of the insulating glass assembly so as to establish a barrier that prevents moisture from penetrating into the interior of the assembly. Insulating sash assemblies are described, e.g., in U.S. Pat. No. 6,286,288. Sealant compositions have also been used to bond an insulating glass assembly, e.g., an insulating glass unit, to a frame. This process is often referred to as “back bedding.” Back bedding is discussed in, e.g., U.S. Pat. Nos. 6,286,288 and 5,856,404 and incorporated herein. In the fabrication of door and window units back bedding sealants are often used to seal and bond panes of glass to retain the pane in position within a frame, to provide a weather proof seal, to reinforce the structural strength of the assembly, or a combination thereof.
A variety of compositions have been used in constructing insulating glass assemblies. One part polyurethane compositions, for example, have been used to bond glass to a variety of substrates relying on the thermoplastic component to supply the green strength, which necessitates higher application temperature. In addition, such one part polyurethane compositions rely on moisture curing reactions for final performance, which tend to be relatively slow.
Dual-cure compositions in which ultraviolet light and moisture are used to cure the composition have been used in a variety of applications including, e.g., structural adhesives as described, e.g., in EP 646632A1, WO 0105846, and WO 98/53008.
A two package UV curable conformal coating has been described in U.S. Pat. No. 5,013,631.
A photocurable resin composition for use in coatings comprising a component with dual functionality, acrylate and silane, is described in EP 0 549 228 B1. This is a low molecular weight compound that is intended to improve adhesion at high temperatures. U.S. Pat. No. 5,478,427 describes adhesives based on macromers having acrylate and isocyanate functionality, but in this case to achieve adhesion the composition has to be applied on both substrates to be bonded.
Other compositions described in U.S. Pat. No. 4,965,117 and known as “command-cure” compositions are applied as a strip or a tape and cured by exposure to ultraviolet radiation.